Statistics
| Branch: | Revision:

ffmpeg / libavcodec / mjpegbdec.c @ 81752d0c

History | View | Annotate | Download (4.52 KB)

1
/*
2
 * Apple MJPEG-B decoder
3
 * Copyright (c) 2002 Alex Beregszaszi
4
 *
5
 * This file is part of FFmpeg.
6
 *
7
 * FFmpeg is free software; you can redistribute it and/or
8
 * modify it under the terms of the GNU Lesser General Public
9
 * License as published by the Free Software Foundation; either
10
 * version 2.1 of the License, or (at your option) any later version.
11
 *
12
 * FFmpeg is distributed in the hope that it will be useful,
13
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15
 * Lesser General Public License for more details.
16
 *
17
 * You should have received a copy of the GNU Lesser General Public
18
 * License along with FFmpeg; if not, write to the Free Software
19
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20
 */
21

    
22
/**
23
 * @file mjpegbdec.c
24
 * Apple MJPEG-B decoder.
25
 */
26

    
27
#include "avcodec.h"
28
#include "mjpeg.h"
29
#include "mjpegdec.h"
30

    
31

    
32
static int mjpegb_decode_frame(AVCodecContext *avctx,
33
                              void *data, int *data_size,
34
                              uint8_t *buf, int buf_size)
35
{
36
    MJpegDecodeContext *s = avctx->priv_data;
37
    uint8_t *buf_end, *buf_ptr;
38
    AVFrame *picture = data;
39
    GetBitContext hgb; /* for the header */
40
    uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;
41
    uint32_t field_size, sod_offs;
42

    
43
    buf_ptr = buf;
44
    buf_end = buf + buf_size;
45

    
46
read_header:
47
    /* reset on every SOI */
48
    s->restart_interval = 0;
49
    s->restart_count = 0;
50
    s->mjpb_skiptosod = 0;
51

    
52
    init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
53

    
54
    skip_bits(&hgb, 32); /* reserved zeros */
55

    
56
    if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))
57
    {
58
        av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");
59
        return 0;
60
    }
61

    
62
    field_size = get_bits_long(&hgb, 32); /* field size */
63
    av_log(avctx, AV_LOG_DEBUG, "field size: 0x%x\n", field_size);
64
    skip_bits(&hgb, 32); /* padded field size */
65
    second_field_offs = get_bits_long(&hgb, 32);
66
    av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%x\n", second_field_offs);
67

    
68
    dqt_offs = get_bits_long(&hgb, 32);
69
    av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%x\n", dqt_offs);
70
    if (dqt_offs)
71
    {
72
        init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8);
73
        s->start_code = DQT;
74
        ff_mjpeg_decode_dqt(s);
75
    }
76

    
77
    dht_offs = get_bits_long(&hgb, 32);
78
    av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%x\n", dht_offs);
79
    if (dht_offs)
80
    {
81
        init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8);
82
        s->start_code = DHT;
83
        ff_mjpeg_decode_dht(s);
84
    }
85

    
86
    sof_offs = get_bits_long(&hgb, 32);
87
    av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%x\n", sof_offs);
88
    if (sof_offs)
89
    {
90
        init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8);
91
        s->start_code = SOF0;
92
        if (ff_mjpeg_decode_sof(s) < 0)
93
            return -1;
94
    }
95

    
96
    sos_offs = get_bits_long(&hgb, 32);
97
    av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%x\n", sos_offs);
98
    sod_offs = get_bits_long(&hgb, 32);
99
    av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs);
100
    if (sos_offs)
101
    {
102
//        init_get_bits(&s->gb, buf+sos_offs, (buf_end - (buf+sos_offs))*8);
103
        init_get_bits(&s->gb, buf_ptr+sos_offs, field_size*8);
104
        s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
105
        s->start_code = SOS;
106
        ff_mjpeg_decode_sos(s);
107
    }
108

    
109
    if (s->interlaced) {
110
        s->bottom_field ^= 1;
111
        /* if not bottom field, do not output image yet */
112
        if (s->bottom_field && second_field_offs)
113
        {
114
            buf_ptr = buf + second_field_offs;
115
            second_field_offs = 0;
116
            goto read_header;
117
            }
118
    }
119

    
120
    //XXX FIXME factorize, this looks very similar to the EOI code
121

    
122
    *picture= s->picture;
123
    *data_size = sizeof(AVFrame);
124

    
125
    if(!s->lossless){
126
        picture->quality= FFMAX(FFMAX(s->qscale[0], s->qscale[1]), s->qscale[2]);
127
        picture->qstride= 0;
128
        picture->qscale_table= s->qscale_table;
129
        memset(picture->qscale_table, picture->quality, (s->width+15)/16);
130
        if(avctx->debug & FF_DEBUG_QP)
131
            av_log(avctx, AV_LOG_DEBUG, "QP: %d\n", picture->quality);
132
        picture->quality*= FF_QP2LAMBDA;
133
    }
134

    
135
    return buf_ptr - buf;
136
}
137

    
138
AVCodec mjpegb_decoder = {
139
    "mjpegb",
140
    CODEC_TYPE_VIDEO,
141
    CODEC_ID_MJPEGB,
142
    sizeof(MJpegDecodeContext),
143
    ff_mjpeg_decode_init,
144
    NULL,
145
    ff_mjpeg_decode_end,
146
    mjpegb_decode_frame,
147
    CODEC_CAP_DR1,
148
    NULL
149
};